Permanently set bridge plug



' Feb. 28, 1967 H. J. URBANOSKY 3,306,362

PERMANENTLY SET BRIDGE PLUG Filed March 11, 1964 2 Sheets-Sheet 1 INVENTOR.

Feb. 28, 1967 ,H. J. URBANOSKY PERMANENTLY SET BRIDGE PLUG 2 Sheets-Sheet 2 flavv/o 4/ 0/7 aux/4y INVENTOR.

BY 5M 7 AffO/F/VE United States Patent 3,306,362 PERMANENTLY SET BRIDGE PLUG Harold J. Urbanosky, Houston, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Mar. 11, 1964, Ser. No. 350,978 12 Claims. (Cl. 166-135) This invention relates to a bridge plug for use in a well bore, and, more particularly, to a bridge plug designed to be set permanently in place within tubing or casing.

A bridge plug typically consists of a mandrel on which an elastomeric packing element is mounted between reversely directed extendible slip elements carried on tapered expander elements, with the slip elements being held in an inoperative first position on the expanders by shear pins, and a body lock which maintains these elements in an operative second position. Setting of such a bridge plug is conventionally accomplished by use of a setting tool which applies oppositely directed forces in such a manner that the packing element is expanded into sealing engagement and the slip elements are extended. into anchoring engagement with a well casing to hold the set bridge plug in place.

In setting such typical bridge plugs with a conventional wireline setting tool, at least one of the slip members is usually extended against and dragged along the casing before the packing element has been completely set, which dragging can break some of the casing-engaging teeth on the slip members. Furthermore, with a wireline setting tool having a tension-stud release, it will be appreciated that such dragging can reduce the degree of expansion of the packing element should the additional drag cause the setting tool to release before the packing element is fully set.

As a conventional bridge plug is being lowered into a cased well, it is not uncommon for an obstruction, such as an internal projection in the casing, to engage the lower slip and force the slip upwardly over the lower expander in such a manner that the lower slip at least slightly expands and perhaps even engages the casing. Heretofore, this particular hazard has often resulted in the premature setting, or at best a partial setting, of the bridge plug which usually requires that the incorrectly located bridge plug be set in place, drilled out, and a new bridge plug again lowered with the hope that it will clear the obstruction and reach its desired depth without being inadvertently set.

With those bridge plugs having slip members frangibly connected together in a ring, upon fragmenting of the ring the slip segments are free to move independently of their companion segments. When such a bridge plug is used in an inclined well bore, it will lay against one side of the casing and, as the slip segments are being set, the segments at the opposite side are advanced further along the expander before engaging the casing than those initially resting against the casing. Thus, the bridge plug will remain eccentrically disposed which may prevent the packing element from sealing completely and uniformly around its periphery.

Moreover, since a bridge plug is conventionally arranged with its lower slips adapted to resist downward movement of the bridge plug and its upper slips being reversely directed to resist upward movement, well pressure acting on the cross-sectional area at the high-pressure end of the mandrel imposes a load thereon which is not effectively resisted by the slip at that end. Instead, this load is transmitted through the packing element to the slips at the opposite end and, accordingly, increases the radial loading of the packing element against the casing. If sufiicient, this added radial loading can bulge or split the casing.

It is also somewhat of a problem to expand an elastomeric packing element uniformly without forming one or more longitudinally spaced corrugations which engage the casing at spaced intervals and often trap well fluids there- 'between which reduces the effectiveness of the sealing engagement.

It is, therefore, an object of the present invention to provide a new and improved bridge plug.

It is a further object to provide a new and improved bridge plug adapted for high-pressure service in well conduits which is provided with new and improved uniformly expanding anchor elements so arranged that most of the load imposed by pressure differentials will be carried by the anchor elements.

These and other objects of the present invention are obtained by a bridge plug which includes upper and lower anchoring elements and expander means for progressively expanding the packing element.

The bridge plug of the present invention consists of a central mandrel carrying at each end thereof opposed anchor elements with each anchor being operatively disposed between an abutment member and a slidable expander member. An elastomeric packing element is disposed between and cooperatively engaged with the expander members in such a manner that the packing element will be progressively expanded as the bridge plug is being set. Means are provided for locking the mandrel in position when the bridge plug is finally set.

Each of the new and improved anchor elements consists of a wall-engaging member having a plurality of radially directed fingers extending outwardly around a deformable annular base portion and a yieldable restraining ring member which is cooperatively mounted around the outer ends of the fingers. The fingers are uniformly arranged around the central axis of the annular base portion of the member and are initially disposed at an acute angle in a frusto-conical configuration around the central axis. Upon application of longitudinally directed forces to the inner ends of the fingers, the wall-engaging members will begin to flatten, which action will extend the fingers radially into anchoring engagement with a casing wall. The y-ieldable restraining rings are for (1) holding the fingers in a retracted position until a force of a predetermined magnitude is applied to the anchor ele ments, which force is at least equal to the force required to substantially expand the packing element, (2) ensuring that each finger moves in unison with the others as they are being extended, and (3) acting as anti-extrusion members after the packing element and fingers are brought into wall-engaging contact to prevent the extrusion or cold-flow of the elastomeric packing elements between the fingers.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates the bridge plug of the present invention, partly in section, in its initial retracted position;

FIG. 2 is a section taken along the line 22 of FIG. 1;

FIG. 3 is a view showing the bridge plug of FIG. 1 as it appears when expanded into sealing and anchoring engagement within a well casing; and

FIG. 4 is a section taken along the line 4-4 of FIG. 3.

Turning now to FIG. 1, an embodiment is shown of a bridge plug constructed in accordance with the principles of the invention with portions thereof in section for purposes of greater clarity.

The mandrel 11 is an elongated, cylindrical member around which is slidably mounted an elastomeric packing sleeve or element 12 provided with internal annular recesses 13, 14 in its outer ends. Oppositely directed lower and upper expander members 15, 16 are slidably mounted around mandrel .11 at opposite ends of packing element 12, with each expander having a reduced-diameter cylindrical end portion 17, 18 complementarily received within packing element recesses 13, 14 and an enlarged, outwardly diverging, frusto-conical base portion 19, 20. End portions 17, 18 are provided to stabilize the expander members 15, 16 against tipping relative to the mandrel. The rearward faces 21, 22 of expanders 15, 16 are flat and respectively engage oppositely directed, hollowed, frusto-conical lower and upper anchor elements 23, 24. Lower and upper anchor elements 23, 24, as will be later described in detail, are initially disposed with their outermost edges engaged around the flattened faces 21, 22 of the enlarged base portions of the expander members 15, 16 and their innermost edges engaged with oppositely directed lower and upper abutment members 25, 26, respectively. The lowermost abutment member 25 rests against an upwardly facing shoulder 27 around the lower end of mandrel 11.

Abutment members 25, 26 are generally cylindrical with each having reduced-diameter and inwardly converging tapered hub portions 28, 29 received within the inner edges of the anchor elements 23, 24. The hub portions 28, 29 of the abutment members 25, 26 are tapered to ensure that the anchor members 23, 24 remain engaged against the abutment members rather than riding loosely on the mandrel 11. Accordingly, it will be appreciated that should an anchor member be longitudinally displaced as the bridge plug is being positioned in a well casing, the tapered hubs will recenter the displaced member when it returns to its original position. Furthermore, as the mandrel travels upwardly during the setting operation, the upper hub 29 prevents the mandrel ratchet teeth 30 from catching on the inner edge of upper anchor member 24.

The upper abutment member 26 is of hardened steel to ensure that as the bridge plug is being set, the tapered hub portion 29 will not deform under the substantial radial load applied thereon by the upper anchor member 24 as it is being flattened and extended against the casing. It will be understood, of course, that should this hub 29 deform, the mandrel would not travel smoothly through the upper abutment member 26.

Upper abutment member 26 has an upwardly directed and outwardly diverging tapered recess 31 which receives a complementarily tapered split-nut 32. Split-nut 32 has upwardly facing ratchet teeth 33 around its axial bore which are cooperatively engaged with downwardly facing ratchet teeth 30 cut around the upper end of mandrel 11. A spring member 34 is operatively engaged between the upper end 35 of split-nut 32 and a snap ring 36, which is in turn held against a downwardly facing circumferential shoulder 37 around the upper end of recess 31. Spring member 34 is preferably an assembly of two opposed springs, with each spring consisting of a single flat ring having resilient projecting tabs which are interlocked with the tabs of the other spring. These springs, when nested together, make a compactly arranged spring member with oppositely directed flattened annular end surfaces.

The upper end of upper abutment member 26 has a reduced-diameter outer portion 38 providing an upwardly facing shoulder 39 which is sized and arranged for receiving the lower end of the outer sleeve or pushing member of a conventional setting tool (not shown). If desired, a frangible shear pin (not shown) may be inserted into a radial bore 40 in reduced-diameter portion 38 of the upper abutment member 26 to releasably connect the setting tool sleeve to the bridge plug. External threads 41 around the upper end of mandrel 11 are provided for coupling to the inner mandrel or pulling member of the setting tool. A reduced-diameter or necked portion 42 near the upper end of mandrel 11 is sized to fail whenever oppositely directed forces of a predetermined magnitude are applied in the well-known manner by the setting tool.

As seen in FIG. 1, the anchor members 23, 24 are initially disposed in a frusto-conical configuration around the central axis of the mandrel 11 to provide an annular clearance around the bridge plug 10 when it is inserted into a well casing. The anchor members 23, 24 are arranged to be longitudinally compressed between their respective abutment members and expander members so that, as illustrated in FIGS. 3 and 4, when completely flattened, the outer edges of the anchor members Will be extended into anchoring engagement with the inner wall of the casing.

The anchor members 23, 24 respectively consist of integrally formed, star-shaped, wall-engaging members 43, 44 with annular yieldable restraining members 45, 46 mounted around the periphery of each of the wall-engaging members.

Each of the integrally formed, star-shaped, wall-engaging elements 43, 44 are identical and include weakened and deformable annular base portions 47, 48 from which uniformly spaced fingers 49, 50 extend radially outwardly. These fingers are initially disposed at an acute angle to the central axes of the wall-engaging members and mandrel. The outer ends of the fingers 49, 50 are cut at an acute angle to the inner faces 51, 52 of the fingers to provide a sharp corner, as at 53, 54, for anchoring engagement with the wall of a casing. A recess 55, 56 is provided in the inner face 51, 52 and at the outer end of each finger to provide a peripheral groove for receiving the annular yieldable restraining members 45, 46.

Wall-engaging members 43, 44 are preferably made of steel with the outer end portions of the fingers being selectively hardened to ensure that the sharp edges 53, 54 will bite into a casing wall.

The inner edges 57, 58 of the annular base portions 47, 48 of the wall-engaging members are preferably cut away and beveled to weaken the base portions, which weakening permits the anchor members to deform easily and adapt to the usual diametrical variations found in conventionally sized tubing or casing. By sizing the anchor members to be tightly engaged between the tapered hubs 28, 29 of the abutment members and the casing wall when extended into engagement with casing having the maximum internal diameter for that particular size of easing, whenever the bridge plug 10 is used in casing of that size but with a smaller internal diameter, the beveled inner edges 57, 58 will mushroom as the anchor members are flattened between the expanders and abutment members.

The yieldable annular restraining members 45, 46 of the anchor elements 23, 24 are frusto-conically shaped members, preferably of steel, and are sized for reception within the peripheral grooves 55, 56 of wall-engaging members 43, 44. It will be appreciated that by varying the dimensions and material of the annular restraining members 45, 46, the strength of these members can be regulated to require a predetermined force for stretching them sufliciently to allow the anchor elements to com;

pletely flatten. Accordingly, the restraining members can be sized Where they will not stretch until the setting forces reach a predetermined magnitude which may be less than, equal to, or greater than the magnitude of force required to completely expand a particular packing element. Thus, by regulating the strength of the restraining members, the degree of expansion of the packing element may be controlled.

Annular restraining members 45, 46, however, are preferably sized and proportioned to restrain the outward extension of fingers 49, 50 until such time that packing element 12 has at least been substantially expanded against the casing. Thus, by properly correlating the amount of force required to displace the packing element to the amount of force required to stretch the restraining members, the anchor elements can be delayed from flattening and engaging the casing until the bridge plug has been shifted to substantially its minimum longitudinal displacement, which delay will prevent the finger ends 53, 54 from being dragged along the casing during the setting operation.

It has been found, furthermore, that the restraint provided by the uniform circumferential expansion of annular restraining members 45, 46 guides each finger and ensures that it moves radially outwardly in unison with the other fingers as they are being extended. It will be appreciated also that by ensuring that all fingers move in unison, no one finger can extend further than the others and become lodged between the casing and bridge plug to prevent the bridge plug from centralizing in a well bore.

Moreover, by disposing restraining members 45, 46 around the outermost extremities of the fingers, when the wall-engaging members are fully extended against a casing wall 59, as illustrated in FIGS. 3 and 4, annular restraining members 45, 46 will substantially close the openings between the fingers and around the outer periphery of expander members 15, 16. Thus, it will be appreciated that annular restraining members 46, 46 also effectively prevent the extrusion or cold-flow of the elastomeric packing element 12 after it has been sealingly engaged with the casing wall.

Turning now to the particular configuration of the ends of the packing element 12 and the mating surfaces of the respective expander members 15, 16, when the bridge plug is being set it will be appreciated that during the initial advancement of the expander members toward one another, only their reduced-diameter portions 17, 18 will be in contact with the outer ends of the packing element. It has been found that by initially applying the longitudinally directed setting forces to only the inner annular cross-sectional area of the elastorneric packing element, only the middle or central peripheral portion of the element will initially expand radially into engagement with the casing.

After the central peripheral portion of the packing element 12 contacts the casing 59 and as the element is progressively foreshortened, it will then progressively expand from this central portion longitudinally outwardly toward each end thereof. Thus, by tapering the expander members, as at 60, 61, away from the ends of the packing element, as the expander members 15, 16 continue to advance, these tapered surfaces 60, 61 will progressively engage the end surfaces 62, 63 of the packing element and successively increase the area of contact as the packing element is foreshortened.

By tapering the base portions 19, 20 of the expander members away from the outer anular end surfaces 62, 63 of the packing element 12, contact of the periphery of the ends of the packing element 12 with the expander members 15, 16 can be delayed until the element is almost fully displaced. Although the packing element ends can be left flat, it is preferred to taper both the element ends and the expander members approximately as shown. The particular mating angles are not critical within reasonable limits so long as the initial longitudinal spacing between the packing element ends and the outer ends of the expander members is not so far that the restraining rings 45, 46 are not sufficiently close to the ends of the fully expanded packing element to prevent extrusion of the element from either end of the bridge plug. Furthermore, there is preferably a divergence of the coengaging tapered surfaces to ensure that contact progresses radially outwardly as the expander members advance toward the packing element ends.

Accordingly, when the central portion of the packing element has initially engaged the casing and as the element is progressively displaced outwardly toward its ends, well fluids will be forced longitudinally outwardly from the constantly diminishing annulus surrounding the packing element. It will be appreciated, therefore, that this progressive longitudinal engagement ensures that the packing element seals against the casing without trapping well fluids therebetween.

When the bridge plug of FIG. 1 is to be operated, a conventional setting tool (not shown) is attached to the upper end of bridge plug 10. The pulling member or inner mandrel of the setting tool is threadedly attached to threads 41 at the upper end of mandrel 11 and the pushing member or outer sleeve of the setting tool is cooperatively engaged with upwardly facing shoulder 39 of upper abutment member 26.

When the bridge plug has been positioned for setting within a well bore, the setting tool is operated in the conventional manner to pull mandrel 11 and lower abutment member 25 upwardly as the setting tool sleeve forces upper abutment member 26 downwardly. As the abutment members 25, 26 advance toward each other, it will be appreciated that gradually increasing and oppositely directed setting forces will be applied through the anchor elements 23, 24 and expander members 15, 16 against the opposite ends of packing element 12, which forces will begin progressively foreshortening and displacing the central portion of the packing element radially outwardly toward the casing wall.

When the packing element has been substantially displaced, the setting forces will have then increased, sufliciently to c ause the restraining members 45, 46 to slowly yield and begin to stretch. When the restraining members begin to stretch, the inner surfaces of the restraining members slide outwardly in unison over the adjacent edges of the expander members 15, 16 as the weakened annular base portions 47, 48 of the wall-engaging members 43, 44 are concurrently deformed and driven toward the expanders 15, 16, which actions begin to flatten the anchor members.

As the anchor elements are being flattened, the final displacement of the packing element 12 continues until its .outer ends are finally displaced into the small annular voids remaining around the enlarged frusto-conical portions of the expander members and engage restraining members 45, 46. The tapered surfaces 60, 61 at the enlarged-diameter ends of the expander members assist in directing the flow of the ends of the elastromeric packing element into these remaining voids.

When restraining members 45, 46 have stretched sufficiently, the hardened tips 53, 54 of the fingers will first contact the casing and the continued travel of the abutment members 25, '26 will subsequently completely flatten the conically formed wall-engaging members against the flat end surfaces 21, 22 of the opposing expander members 15, 16 to drive the hardened finger tips into the casing. When the hardened tips 53, 54 are driven into the casing 59, the outer peripheral edges of the annular restraining members 45, 46 will be flattened against the casing 59 to substantially fill any slight irregularities in the casing wall at that point. Furthermore, as seen in FIG. 3, it will be noted that expander members 15, 16 are so proportioned that when the bridge plug 10 is fully set, the frusto-conical portions of the expander members extend radially to a point intermediate the casing wall and the shoulders 64, 65 of the finger grooves 55, 56. Thus, it will be appreciated that annular restraining members 45, 46 completely close any sectorial space between the fingers 49, 50 which would otherwise exist between the outer periphery of expander members 15, 16 and the easing wall 59.

When the setting tool is actuated and as the mandrel 11 first begins to travel upwardly, ratchet teeth 30 on the mandrel 11 will slide under ratchet teeth 33 on split-nut 32 to expand the split-nut. Accordingly, split-nut 32 is free to alternately expand and contract, and each time it expands, it will begin sliding relatively upwardly and outwardly along the tapered surface 31 of upper abutment member 26. As split-nut 32 begins to slide upwardly, however, spring member 34 is compressed and then expands to drive the split-nut inwardly and downwardly to force ratchet teeth 33 into engagement with the next group of ratchet teeth 30 around the mandrel. This alternate compression and expansion of spring member 34 tends to drive split-nut 32 downwardly while preventing any backlash or retrograde movement of the packing element. It will be appreciated, therefore, that splitnut 32 will be continuously driven over the lowermost ratchet teeth 30 of the mandrel that the nut can engage.

After the bridge plug has been completely set into anchoring and sealing engagement with the casing, the setting tool forces continue to increase until weakened portion 42 of mandrel 11 fails, which failure will release the mandrel 11 from the setting tool and allow the setting tool to be retrieved in the conventional manner. When bridge plug is finally anchored and the setting tool disengaged, it will be appreciated that the bridge plug will effectively resist either upwardly or downwardly directed forces.

It should be noted that by preventing the anchor elements from being completely flattened until the packing element has been displaced against the casing, the outer ends 53, 54 of the fingers will not contact the casing 59 until the bridge plug 10 has nearly reached its minimum longitudinal dimension. Then, when the outer finger ends do engage the casing, the inner end of each finger 49, 50 effectively pivots around its outer end 53, 54 as the anchor elements are finally flattened. Thus, it will be appreciated that the casing-engaging portions of the anchor elements are not dragged across the casing wall but instead remain where they first engage the casing.

With any bridge plug having an elastromeric packing element, it will be appreciated that a longitudinally directed force on the packing element will proportionately increase the radial loading of the element against the casing. Thus, when there is a pressure differential across a bridge plug, pressure is applied on the annular crosssectional are-a of the packing element which increases the casing loading. This pressure is also applied on the circular cross-section of the mandrel. With a conventionally arranged bridge plug, since any load on the mandrel is transmitted through the packing element to the slip member opposing forces acting in that direction, this latter pressure force further increases the loading against the casing.

It will be appreciated, however, that with the bridge plug of the present invention, a load on the mandrel is not imposed on the packing element but is instead transmitted directly to the anchor element opposing forces acting in that direction. For example, an upwardly directed load on the mandrel is directly transmitted from the mandrel 11 and lower abutment member into lower anchor element 23 is engaged against the casing 59 in such a manner as to oppose upwardly directed forces. Similarly, a downwardly directed force is transmitted directly to the upper anchor element 24. Thus, once the bridge plug 10 of the present invention is set, pressure forces acting on the mandrel will not be transmitted through the packing element 12 which, accordingly, reduces the likelihood that additional loading of the element might bulge or split the casing or perhaps crack cement behind the casing.

Accordingly, it will be appreciated that a bridge plug constructed in accordance with the present invention will be suitable for high-pressure service in well conduits with the anchor members carrying most of the additional loads imposed thereby. Furthermore, the anchor elements will expand uniformly to provide a uniform loading against the casing as well as to ensure that the bridge plug is centralized within the casing. The anti-extrusion rings 45, 46 of the present invention will further ensure that an elastomeric packing element will not extrude from around the packer body. It will be further appreciated that the packing element will progressively expand against the casing to ensure full and efifective sealing engagement therewith without trapping Well fluids therebetween.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; a wall-anchoring member having an annular base portion with a plurality of fingers extending radially outwardly therefrom having outer end portions adapted for engaging a well bore, said mandrel being slidably extended through said annular base portion, said fingers being uniformly arranged around one end of said base portion and initially disposed in a first position at an acute angle to the central axis of said mandrel with said outer end finger portions arranged for engagement with said expander member; and means on said mandrel for engaging said anchoring member base portion at the opposite end thereof, said anchoring member being responsive to longitudinal advancement of said engaging means relative to said expander member to shift said fingers from said first position to a second position substantially at right angles with said central axis to extend said outer end finger portions into engagement with a well bore.

2. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular expander member slidably .mounted around said mandrel and operatively engaged with an end of said packing element; a wall-anchoring member having a deformable annular base portion with a plurality of integrally formed fingers extending radially outwardly therefrom having outer end portions adapted for engaging a well bore, said mandrel being slidably extended through said annular base portion, said fingers being uniformly arranged around one end of said base portion and initially disposed in a first position at an acute angle to the central axis of said mandrel with said outer end finger portions arranged for engagement with said expander member; and means on said mandrel for engaging said anchoring member base portion at the opposite end thereof, said anchoring member being deformable in response to longitudinal advancement of said engaging means relatively toward said expander member to shift said fingers from said first position to a second position substantially at right angles with said central axis to cxtend said outer end finger portions into engagement with a well bore.

3. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; a wall-anchoring member having a deformable annular base portion with a plurality of integrally formed fingers extending radially outwardly therefrom having outer end portions adapted for engaging a well bore, said mandrel being slidably extended through said annular base portion, said fingers being uniformly arranged around one end of said base portion and initially disposed in a first position at an acute angle to the central axis of said mandrel with said outer end finger portions arranged for engagement with said expander member; means on said mandrel for engaging said anchoring member base portion at the opposite end thereof, said anchoring member being deformable in response to longitudinal advancement of said engaging means relatively toward said expander member to shift said fingers from said first position to a second position substantially at right angles with said central axis to extend said outer end finger portions into engagement with a well bore; and means restraining said outer end finger portions and yielding in response to forces of a predetermined magnitude against said members.

4. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; a wall-anchoring member having an annular base portion with a plurality of fingers extending radially outwardly therefrom having outer end portions adapted for engaging a well bore, said mandrel being slidably extended through said annular base portion, said fingers being uniformly arranged around one end of said base portion and initially disposed in a first position at an acute angle to the central axis of said mandrel with said outer end finger portions arranged for engagement with said expander member; and engaging means on said mandrel having a tapered hub portion converging toward said mandrel and cooperatively engaged within said anchoring member base portion at the opposite end thereof for centralizing said anchoring member, said anchoring member being responsive to longitudinal advancement of said engaging means relative to said expander member to shift said fingers from said first position to a second position substantially at right angles with said-central axis to extend said outer end finger portions into engagement with a Well bore.

5. In a packer device having an annular, elastomeric packing element of a first outer diameter operatively mounted around a mandrel and adapted for expansion to a second greater diameter into sealing engagement with a well bore, the improvement comprising: an annular expander member slidably mounted around said mandrel and .operatively engaged with an end of said packing element; a well-anchoring member having a deformable annular base portion with a plurality of integrally formed fingers extending radially outwardly therefrom having outer end portions adapted for engaging a well bore, said mandrel being slidably extended through said annular base portion, said fingers being uniformly arranged around one end of said base portion and initially disposed in a first position at an acute angle to the central axis of said mandrel with said outer end finger portions arranged for engagement with said expander member and circumscribing a circle having a diameter substantially equal to said first diameter, each of said fingers having a recess in a face thereof providing an outwardly facing circumferential shoulder around said outer end finger portions at a diameter less than said first diameter; engaging means on said mandrel having a tapered hub portion converging toward said mandrel and cooperatively engaged within said anchoring member base portion at the opposite end thereof for centralizing said anchoring member, said anchoring member being deformable in response to longitudinal advancement of said engaging means relatively toward said expander member to shift said fingers from said first position to a second position at substantially right angles with said central axis to extend said outer end finger portions to a diameter substantially equal to said second diameter and into engagement with a well bore; and means yieldably restraining such longitudinal advancement of said members and shifting of said fingers and responsive to oppositely directed longitudinal forces of a predetermined magnitude against said members including an expansible ring member received in said recesses and engaged with said circumferential shoulders around said outer end finger portions.

6. The packer device of claim 5 in which said expansible ring member is extended outwardly to the outermost ends of said finger members for engagement with a well bore in said second finger position whereby said ring member substantially obstructs the sectorial openings between said extended fingers to prevent cold-flow of said elastomeric packing element through such openings when said packing element is expanded into sealing engagement.

7. The packer device of claim 6 wherein said expansible ring is sized and arranged to restrain said fingers from completely shifting to said second position in response to such forces until said packing element has been substantially expanded to said second diameter.

8. As a subcombination, an expansible anchor assembly adapted for extension into engagement with a well bore, said anchor assembly comprising: a well-engaging member having a deformable annular base portion sized and adapted for mounting around a mandrel with a plurality of equally spaced fingers uniformly extending radially outwardly in a first position at an acute angle to the central longitudinal axis of said wall-engaging member, each of said fingers having a recess in a face of the outer end portion of said fingers providing an outwardly facing peripheral shoulder around said outer end portions; and an annular yieldable restraining member received in said recesses and engaged with said peripheral shoulders around said outer end portions, said anchor assembly being responsive to concurrent application of a first force against the outer ends of said fingers in a direction toward said base portion and parallel to said central axis and a second force opposite to said first force against said base portion to deform said base portion and circumferentially expand said restraining member as said fingers are uniformly extended to a second position substantially perpendicular to said central axis.

9. In a packer device having a packing element operatively mounted around a mandrel and adapted for expansion to seal off a well bore, the improvement comprising: anchor means on said mandrel for anchoring said device in a well bore upon expansions of said packing element, said anchor means including a star-shaped member with separate finger elements initially disposed at an acute angle to the central axis of said mandrel and movable toward a position at right angles to said central axis where the ends of said finger elements lockingly engage the wall of a well bore; and expander means on said mandrel movable relative to and engaging said anchor means for moving said finger elements toward said position where the ends of said finger elements lockingly engage the wall of a well bore.

10. In a packer device having a packing element operatively mounted around a mandrel and adapted to seal off a well bore and expander means on said mandrel for expanding said packing element, the improvement comprising: anchor means on said mandrel for anchoring said device in a well bore upon expansion of said packing element, said anchor means including a star-shaped member with separate finger elements initially disposed at an acute angle to the central axis of said mandrel and movable to ward a .position at right angles to said central axis where the ends of said finger elements lockingly engage the wall of a well bore; and ring means for restraining such movement of said finger elements toward said position and yieldable in response to predetermined forces, said ring means maintaining a ring-like configuration when said finger ends engage the wall of a well bore.

11. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore and expander means on said mandrel for expanding said packing element, the improvement comprising: annular wall-anchoring means including a plurality of individual, elongated circumferentially spacedapart members uniformly spaced around the central axis of said mandrel, said elongated members having outer wa1l-engaging portions and being yieldably joined to adjacent ones of said members and operatively arranged for circumferential expansion of said wall-anchoring means; and expansible ring means around the periphery of said wall-anchoring means for yield ably restraining the circumferential expansion of said wall-anchoring means, said wall-anchoring means being operatively disposed on said mandrel in cooperative relationship with said expander means and responsive to relative longitudinal movement therebetween to circumferentially expand said wallanchoring means and expansible ring means whereby said members move radially outwardly into anchoring engagement with the wall of a well bore.

12. The packer device of claim 11 wherein said expansible ring means is sized and arranged to restrain full circumferential expansion of: said wall-anchoring means until said packing element has been substantially expanded into sealing engagement.

References Cited by the Examiner UNITED STATES PATENTS 1,050,557 l/1913 McLaughlin 166192 X 2,791,278 5/1957 Clark 2779.5 X 2,836,252 5/1958 Lane 277-116.2 2,857,972 10/1958 Baker 277-116.2 2,862,563 12/1958 Thompson 277-9.5 3,061,012 10/1962 Moosman 277-1l6.2 3,068,942 12/1962 Brown 277116.2 X

CHARLES E. OCONNELL, Primary Examiner.

D. H. BROWN, Assistant Examiner. 

9. IN A PACKER DEVICE HAVING A PACKING ELEMENT OPERATIVELY MOUNTED AROUND A MANDREL AND ADAPTED FOR EXPANSION TO SEAL OFF A WELL BORE, THE IMPROVEMENT COMPRISING: ANCHOR MEANS ON SAID MANDREL FOR ANCHORING SAID DEVICE IN A WELL BORE UPON EXPANSIONS OF SAID PACKING ELEMENT, SAID ANCHOR MEANS INCLUDING A STAR-SHAPED MEMBER WITH SEPARATE FINGER ELEMENTS INITIALLY DISPOSED AT AN ACUTE ANGLE TO THE CENTRAL AXIS OF SAID MANDREL AND MOVABLE TOWARD A POSITION AT RIGHT ANGLES TO SAID CENTRAL AXIS WHERE THE ENDS OF SAID FINGER ELEMENTS LOCKINGLY ENGAGE THE WALL OF A WELL BORE; AND EXPANDER MEANS ON SAID MANDREL MOVABLE RELATIVE TO AND ENGAGING SAID ANCHOR MEANS FOR MOVING SAID FINGER ELEMENTS TOWARD SAID POSITION WHERE THE ENDS OF SAID FINGER ELEMENTS LOCKINGLY ENGAGE THE WALL OF A WELL BORE. 